What is PGE SeaState and how is it generated?.

PGE SeaState is a weather forecast and climatology system that was designed and built by Dr. Les Bender specifically for use at PGE's Diablo Canyon Power Plant. Dr. Bender has extensive experience in operational meteorology and oceanography. He saw the need for an specialized weather product that focused on providing real-time sea state information specifically tailored for operations at sea. The web page is not visually impressive; it was not meant to be. It was designed to convey the weather information needed to make daily and long-term operational decisions in a compact format that had no ads or click-through’s.

The information presented in PGE SeaState is not provided by a professional third party source, but is downloaded directly from the data made available by NOAA's National Centers for Environmental Prediction (NCEP) and the Copernicus Marine Service (CMEMS). This is the same source as used by popular weather apps such as Windy, Weather Underground, AccuWeather, WeatherBug, the Weather Channel, etc. The difference with PGE SeaState is you know where the forecast data is coming from; through a verifiable, direct link to the source.

There are three major components to PGE SeaState:

• Waves and Winds
• Ocean
• Atmosphere

Waves and Winds: The operational wave and wind forecasts uses five unique wave models: GFS, GEFS, NWPS, WAM, and SWAN.
1) GFS: The NCEP/EMC global deterministic wave model is unified into NOAA's Global Forecast System (GFS). We use the west coast post-processed grid. The WAVEWATCH III spectral wave model is one way coupled to the atmospheric forecast model. In addition, surface ocean currents from the Global Real-Time Ocean Forecast System (RTOFS) are input to the wave model. The model is run by NCEP four times a day: 00Z, 06Z, 12Z, and 18Z and produces hourly forecasts out to 120 hours and every 3 hours from 120 to 384 hrs (5-16 days). There are three native computational grids, one for the arctic, one for one for the northern hemisphere (15S to 52.5N), and one for the southern hemisphere (10.5S to 79.5S) and four post-processed grids, one of them being for the west coast.
2) GEFS: The NCEP/EMC Global Ensemble Ocean Wave Forecast System. Due to uncertainty of the forcing wind fields, ocean wave models have a finite limit of perdictability. The GEFS wave model is unified with the GFS wave model, but has 30 different wind fields, one initial wave field, and 30 separate runs to track the evolution of the wave environment. The GEFS results presented here are the mean of those 30 individual runs. The purpose of GEFS is to reliably extend long-range predicitions.
3) NWPS: The Nearshore Wave Prediction System (NWPS) provides on-demand, high-resolution nearshore wave model guidance to US coastal Wave Forecasting Offices (WFO), such as Los Angeles which is responsible for the wave model covering Diablo Canyon. Each individual office prepares the forecast wind fields and submits them to NCEP'S Environmental Modeling Center (EMC). The wave boundary conditions are from the operational WaveWatch-III model. The nearshore wave model used is SWAN. Tides and storm surge are accounted for. Wave-current interaction is included using surface currents from the Real-Time Ocean Forecast System. The computational grids have a nearshore resolution of 1.8 km down to 500m. Details of the specific bathymetry used is not provided. From the perspective of pedigree, this model has it all.
4) WAM: The global wave system of Météo-France is based on the wave model MFWAM which is a third generation wave model. MFWAM uses the computing code ECWAM-IFS-38R2 with a dissipation terms developed by Ardhuin et al. (2010). The model MFWAM was upgraded on November 2014 thanks to improvements obtained from the european research project « my wave » (Janssen et al. 2014). The model mean bathymetry is generated by using 2-minute gridded global topography data ETOPO2/NOAA. Native model grid is irregular with decreasing distance in the latitudinal direction close to the poles. At the equator the distance in the latitudinal direction is more or less fixed with grid size 1/10°. The operational model MFWAM is driven by 6-hourly analysis and 3-hourly forecasted winds from the IFS-ECMWF atmospheric system. The wave spectrum is discretized in 24 directions and 30 frequencies starting from 0.035 Hz to 0.58 Hz. The model MFWAM uses the assimilation of altimeters with a time step of 6 hours. The global wave system provides analysis 4 times a day, and a forecast of 10 days at 0:00 UTC. The wave model MFWAM uses the partitioning to split the swell spectrum in primary and secondary swells.
5) SWAN: Simulating WAves Nearshore is a third-generation wave model, developed at Delft University of Technology, that computes random, short-crested wind-generated waves in coastal regions and inland waters. In addition to the NWPS use of SWAN (see above) we run a SWAN model using a localized, high-resolution grid and drive it with GFS winds. SWAN accounts for the following physics:

• Wave propagation in time and space, shoaling, refraction due to current and depth, frequency shifting due to currents and non-stationary depth.
• Wave generation by wind.
• Three- and four-wave interactions.
• Whitecapping, bottom friction and depth-induced breaking.
• Dissipation due to aquatic vegetation, turbulent flow and viscous fluid mud.
• Wave-induced set-up.
• Propagation from laboratory up to global scales.
• Transmission through and reflection (specular and diffuse) against obstacles.
• Diffraction.

The operational skill - forecasted wave heights within 1.5 foot (0.45 m) of the actual wave height recorded by a wave buoy - is typically excellent out to 3 days, good at 3 - 5 days, poor from 5 - 7 days, and statistical noise for any forecast longer than 7 days. Forcasting any weather conditions more than seven days out is usually fruitless. A comparison of wave forecasts compared to NDBC wave buoy data can be seen Wave Model Validation

Ocean: The operational ocean current, temperature and salinity forecasts use (RTOFS). RTOFS is based on an eddy resolving 1/12 degree global HYCOM (Hybrid Coordinates Ocean Model) that serves as the backbone of the National Weather Service's operational ocean system. The model runs once a day and produces a nowcast and eight days of forecasts. There is a single computational grid for the globe. As of 13 September 2024 the straigthforward means of obtaining vertical profile data was terminated; only the surface currents, temperature and salinity is readily accessible.

Atmosphere: The operational atmospheric forecasts use the Global Forecast System (GFS). The entire globe is covered by the GFS at a base horizontal resolution of 28 km. The model is run by NCEP four times a day: 00Z, 06Z, 12Z, and 18Z.  Each run produces forecasts of every 3 hours from the initial time out to 16 days. 

In addition to the three major components there are a number of additional components:

• Sea Level
• Sound Speed
• Absorption Coefficients
• Weather Resources
• Bathymetry

Sea Level: The sea level tidal height variations and transports are generated with the OSU TXPO Tide Models. TXPO is a series of fully global models of ocean tides, which best fits, in a least squares sense, the Laplace Tidal Equations and satellite altimetry data.

Weather Resources: A link to additional weather resources such as visible satellite images, radar images, frontal analysis, and nearby NDBC wave buoys.

Bathymetry: Finally, there is an option to show the bathymetry from available DEM models, ETOPO1, GEBCO30, GEBCO 2019, SRTM15, and GMRT, as well as the (coarse) bathymetry of the RTOFS model. This option must be requested.